In order to efficiently market grain, seeds and similar granular materials, both the quantity and the quality must be determined in accordance with accepted measurement standards. Methods for determining the quantity of these materials are currently automated and are sufficiently accurate. However, the methods currently used for measuring quality are subjective and labor intensive. In addition, inhalation of grain dust results in a threat to the prolonged health of the grain quality inspectors.
The prior art includes attempts to automate various quality tests, however, these attempts have not been successful. One of such attempts to automate the testing of grains is shown in U.S. Pat. No. 3,545,281 issued to John A. Johnston. This apparatus uses a vibrating feeder and a weighing station to supply a preselected weight of sample to a set of separating screens. The separating screens separate the oversize particles and the undersize particles from the normal size range of grain particles. The over or undersized particles are conducted to a fraction weighing station where the over or undersigned particles are weighed and this weight is compared with the weight of the entire sample.
This procedure seriously alters the homogeneity of the diverse particulate materials in the original sample and can thereby introduce errors. Since only a preset amount and not the entire sample can be analyzed at a given time, the mixture of foreign material in the analyzed portion may differ from the remaining unanalyzed portion of the sample. This can lead to an error in the overall evolution of the sample. Another disadvantage of this apparatus is related to the inconvenience of analyzing only samples weighing more than the apparatus' preset amount. Consequently, there is no way of evaluating samples which are smaller than the preset amount and yet may be a sufficiently valid representative sample for the desired test.